Tillage effects on plant available water, cotton production, and soil and water quality

A cooperative project between

USDA Agricultural Research Service Southeast Watershed Research Laboratory
and the
The University of Georgia Crop and Soil Science Department

Developing Solutions for Today's Cotton Production Systems

Project Overview Today's cotton producers are faced with many challenges. Price instability requires growers to continue to lower production costs while maintaining yields. Wherever possible inputs must be reduced and at the same time, efficiency, especially in water use, increased. Producers must also respond to pressure to minimize impacts of farming practices on surface and groundwater quality. Producers need information regarding solutions to these potential problems to make economically and environmentally responsible decisions that will affect their viability.

Conventional Tillage Plots

This research is designed to provide guidance and assistance in these matters. It involves a long-term systematic comparison of cotton production under conventional and conservation tillage on a Coastal Plain soil which is vulnerable to erosion. The study will examine the effects of tillage and poultry litter application upon cotton yield, soil-water storage, surface and subsurface water quality, and soil-quality over a long term period.

Strip Till Plots

Goals

• compare water use efficiency under conventional and conservation tillage
• determine impacts of tillage and management on soil and water quality
• compare the economic return of different cotton production systems
• quantify the effects of strip till on organic matter in Coastal Plain soils
• develop an economically and environmentally feasible production system using poultry litter for cotton production
• assess efficacy and potential impacts on water quality of pesticides, defoliants, and other harvest-aid chemicals

Preliminary Results

• greater runoff and sediment loss was observed from conventionally tilled plots
• higher rates of infiltration were observed under conservation tillage and as a result more water was available for plant growth
• pre-plant herbicides degraded at the same rate under both tillage systems
• pre-plant broadcast application of poultry litter on the strip tilled plots resulted in significant litter loss in runoff

Instrumentation, Engineering, and Resources

Replicated plots are fully instrumented so that impacts of management practices on the quantity of water that is available for the crop and the quality of the water leaving plots can be evaluated. Instrumentation includes:

• devices for continuous monitoring of soil water content
• automated surface runoff collectors
• ground water monitoring wells on each plot
• subsurface drains to permit monitoring lateral subsurface flow
• a perimeter drain to prevent interference from up-gradient farming activities
• state of the art facilities for pesticide analysis

Supporting Organizations   Georgia Cotton Commission   U.S. Department of Agriculture   University of Georgia Contacts Dr. David Bosch, Hydraulic Engineer Dr. Tom Potter, Environmental Chemist Dr. Clint Truman, Soil Scientist USDA-Agricultural Research Service, Southeast Watershed Research Laboratory 2375 Rainwater Road Tifton, Georgia   31794 ph: 229-386-3515 Dr. Craig Bednarz, Cotton Physiologist Dr. Glen Harris, Extension Soil Fertility University of Georgia Crop and Soil Science Department Coastal Plain Experiment Station Tifton, Georgia   31794 ph: 229-386-3360